INVESTIGATION OF A UNIQUE TIME-SPACE CLUSTER OF SARCOIDOSIS IN FIREFIGHTERS

A unique cluster of three cases of sarcoidosis developed recently amon g 10 white firefighters who trained together as apprentices in 1979. T his led us to hypothesize that firefighters are at increased risk of t his condition because of the combined effect of smoke exposure and inf ection with a communicable agent, such as Chlamydia pneumoniae, a rece ntly proposed cause of sarcoidosis. We conducted a case-finding questi onnaire survey of 1,282 active and retired male Providence firefighter s and police officers and then evaluated both the index apprenticeship class and two control cohorts by chest radiography, seromarkers of T lymphocyte activation (neopterin and sIL-2R), and chlamydial serology One additional case of sarcoidosis was identified among the 990 (77%) survey respondents. No new cases were detected in the subsequent labor atory investigation of 46 (87%) firefighters from the index 1979 appre nticeship class, 53 (75%) firefighter controls from the 1974 and 1980 classes, or 50 (30%) police officer controls from 1973-1981 classes. T he cohorts did not differ with regard to either C. pneumoniae antibody titers or sIL-2R levels, but serum neopterin was elevated (> 9.0 nmol /L) in 20% (eight of 41) of the index cohort, 22% (11 of 51) of firefi ghter controls, and 4% (two of 48) of police officers. Logistic regres sion found firefighting to be the only significant predictor of neopte rin elevation (odds ratio 5.8; 95% Cl, 1.3 to 26.9). Our results sugge st that firefighters may be at risk of T lymphocyte activation. Determ ining whether this reflects an enhanced risk of lymphocytic alveolitis and whether firefighters are more likely to develop sarcoidosis requi res further study.